I'm not sure because I haven't had such a rain gauge for a long time, but I seem to remember that the inner tube of a Nylex 250mm gauge was calibrated in points down one side and mm down the other. These gauges are still available I believe.

I'm not sure because I haven't had such a rain gauge for a long time, but I seem to remember that the inner tube of a Nylex 250mm gauge was calibrated in points down one side and mm down the other. These gauges are still available I believe.

I have a Nylex 250mm gauge, probably 10 years old now, but sadly mine is only calibrated for millimetres. I'm pretty sure all the newer ones are similar.